摘要
建立了无汞双波长等吸收分光光度法测定化学需氧量(COD)的方法,以445 nm为测定波长、545 nm为参比波长,可有效消除Cr(Ⅲ)和AgCl沉淀对重铬酸钾吸光度的影响。结果表明:HgSO_(4)和Ag_(2)SO_(4)共存时,HgSO_(4)会削弱Ag_(2)SO_(4)掩蔽Cl-的效果;COD不大于800 mg/L,1∶100的Ag_(2)SO_(4)-H2SO4(即1.0 g Ag_(2)SO_(4)加入100 mL浓H2SO4配制)能测定Cl-不大于2000 mg/L的水样,调整Ag_(2)SO_(4)-H2SO4为2∶100(即2.0 g Ag_(2)SO_(4)加入100 mL浓H2SO4配制),能测定Cl-不大于5000 mg/L的水样。该方法用于高氯水的标准和实际样品分析,结果满意。该方法不分COD高低量程和过滤,节约试剂成本,降低危险性,简化操作步骤,便于废液回收处理。
A mercury-free dual-wavelength equal-absorption spectrophotometric method for the determination of chemical oxygen demand(COD)was developed.Using 445 nm as the measurement wavelength and 545 nm as the reference wavelength,the interference from Cr(Ⅲ)and AgCl precipitation on the absorbance of potassium dichromate was effectively eliminated.The results demonstrated that HgSO_(4)weakened the masking effect of Ag_(2)SO_(4)on Cl-when both HgSO_(4)and Ag_(2)SO_(4)were present.For COD concentrations not exceeding 800 mg/L,a 1∶100 Ag_(2)SO_(4)-H 2SO 4 solution(prepared by adding 1.0 g Ag_(2)SO_(4)to 100 mL concentrated H 2SO 4)could be used to analyze water samples with Cl-concentrations up to 2000 mg/L.By adjusting Ag_(2)SO_(4)-H 2SO 4 to 2∶100(prepared by adding 2.0 g Ag_(2)SO_(4)to 100 mL concentrated H 2SO 4),water samples with Cl-concentrations up to 5000 mg/L could be analyzed.This method was applied to the analysis of both standard and real-world high-chlorine water samples,yielding satisfactory results.This method enabled the accurate determination of COD without the need to differentiate between high and low COD ranges or apply filtration in high-chlorine water.Moreover,it offered advantages such as reduced reagent costs,minimized hazards,simplified operational procedures,and enhanced waste liquid recycling and treatment.
作者
杨孝容
先昱熹
张文
张蓉
曾睿彤
唐琼
YANG Xiaorong;XIAN Yuxi;ZHANG Wen;ZHANG Rong;ZENG Ruitong;TANG Qiong(College of New Energy Materials and Chemistry,Leshan Normal University,Leshan Sichuan 614000;Research Center of Pollution Control and Resource Utilization in South Sichuan,Leshan Sichuan 614000)
出处
《环境污染与防治》
北大核心
2025年第2期96-100,107,共6页
Environmental Pollution & Control
基金
四川省第二批地方普通本科高校应用型示范课程(No.2020-44)
四川省第二批省级一流本科课程(No.2021-979)。
关键词
化学需氧量
无汞
双波长等吸收分光光度法
高氯水
chemical oxygen demand
mercury-free
dual-wavelength equal-absorption spectrophotometric method
high-chlorine water
